1. Field of the Invention
The present invention relates to a syringe assembly devised to reduce the risk of an accidental needle prick. The syringe assembly includes a sheath which is slidably engagable with a needle lock and hub assembly so as to permit the sheath to be axially adjustable to selectively lock the sheath in or unlock the sheath from a protective posture, thus concealing and exposing the needle, respectively.
2. Description of the Prior Art
Health care professionals have become increasingly susceptible to the hazards associated with accidental needle strikes during the sheathing of a syringe after an injection has been completed. It has been found that infectious diseases can be transmitted through the handling or disposal of syringes after use. Accidents caused by inadvertent needle pricks may require a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiencies associated with these tests could result in considerable waste, which may be particularly damaging to a health care facility which is striving to cut costs.
Protective sleeves for syringes are well known in the art. One such sleeve is shown in U.S. Pat. No. 4,790,827 issued Dec. 13, 1988 to Terry M. Haber et al. Haber et al. disclose several species of a shielded safety syringe having a protective sleeve engaging a syringe barrel and including a plurality of different locking and guide means which cooperatively guide and lock the sleeve relative to the barrel, none of which are similar to the instant invention described hereinafter.
U.S. Pat. No. 4,826,490 issued May 2, 1989 to Phillip O. Byrne et al. describes safety device for a hypodermic needle having a sheath slidably engagable with a needle housing. The sheath includes a spigot which slides along a channel in the housing and engages a well to lock the sheath in a position concealing the needle.
U.S. Pat. No. 4,850,977 issued Jul. 25, 1989 to William B. Bayless teaches a spring biased sheath held in check by a latch mechanism which when released, will enable the sheath to enclose the needle within the sheath.
U.S. Pat. No. 5,002,533 issued Mar. 26, 1991 to Robert G. Jullien shows a sheath axially extendable from the barrel of a syringe for concealing a needle therein. The sheath must be rotated relative to the barrel in order to lock the sheath in the extended position.
U.S. Pat. No. 5,030,209 issued Jul. 9, 1991 to Alan A. Wanderer et al. describes a protective sheath slidably engaging the needle support. The sheath has a slot with widened openings at either end while the needle support includes a depressible tab having a wider portion which will fit in either of the wider portions of the slot so as to lock the sheath in either a retracted or extended position.
U.S. Pat. No. 5,045,066 issued Sep. 3, 1991 to Gustav A. Scheuble et al. shows a needle with a protective sheath. A hub mountable on the base of the barrel has diametrically opposed tabs engagable with openings in the sheath to lock in the sheath an extended position.
U.S. Pat. No. 5,088,986 issued Feb. 18, 1992 to Michael J. Nusbaum discloses a safety syringe having an actuator operable by rotating a handle to shift a sheath to a retracted position, compressing a spring. A latch locks the sheath and the actuator in the retracted position. By releasing the latch, the actuator and the sheath are returned to the extended position, concealing the needle.
U.S. Pat. No. 5,106,379 issued Apr. 21, 1992 to E. Jack Leap shows a syringe assembly having a sheath that is slidably carried by the barrel of the syringe. A latch is provided to retain the sheath in a retracted position. By pushing up on the latch, the sheath is released to extend and conceal the needle. The sheath includes an L-shaped slot which receives a boss projecting from the barrel. To lock the sheath into an extended position, the sheath must be rotated to move the boss into the small leg of the L.
U.S. Pat. No. 5,116,326 issued May 26, 1992 to David A. Schmidt teaches an hypodermic needle sheath having an extension. The extension has two spaced apart grooves which engage a flange located on the barrel to hold the sheath in an extended or a retracted position.
None of the above inventions and patents, taken either singly or in combination, is seen to disclose or suggest the instant invention as claimed.